1. Field of the Invention
This invention relates to compositions containing an active or functional organic compound which requires solubilization, and more particularly, to such compositions which are effectively solubilized by addition of an aryl phenylethyl ester as solvent, cosolvent or additive.
2. Description of the Prior Art
Many commercial products, e.g. personal care, e.g. sunscreens, pharmaceutical, agricultural and industrial compositions, contain active or functional materials which require solubilization in the form of a solution, emulsion or dispersion, in aqueous or non-aqueous form. For example, a sunscreen formulation containing aromatic compounds such as avobenzone (Escalol® 517) and/or benzophenone-3 (Escalol® 567) as active UVA/UVB absorbing ingredients, requires a solubilization agent to keep it in an emulsion, i.e. to prevent crystallization. Several such solubilizers are known, e.g. ethyl benzoate or a C12–C15 alkyl benzoate; however, the former compound is a strong irritant, and the latter is only a poor solvent for avobenzone.
Previous syntheses of 2-phenylethyl benzoate have employed toxic solvents and/or expensive or toxic stoichiometric reagents. For example, 2-phenylethyl alcohol and benzoic acid have been condensed in acetonitrile solvent with the aid of a stoichiometric N,N,N′,N′-tetramethylchloroformamidinium chloride reagent, prepared in situ from N,N,N′,N′-tetramethylurea, oxalyl chloride and pyridine (Fujisawa et al., Chem. Lett. 1982, 1891–1894). (Oxalyl chloride is a toxic liquid and generates carbon monoxide, a toxic gas.) Similarly, they have been condensed in tetrahydrofuran solvent with the aid of a stoichiometric 3-methylbenzothiazole-2-selone/diethyl azodicarboxylate/N,N-dimethylaniline reagent (Mitsunobu et al., Chem. Lett. 1984, 855–858), and they have also have been condensed with the aid of a stoichiometric triphenylphosphine/S-benzyl-S-phenyl-N-p-tosylsulfilimine reagent (Aida et al., Chem. Lett. 1975, 29–32). (The selenium and phosphorous by-products create a toxic waste problem.) They have also been condensed in toluene with catalytic toluenesulfonic acid, prepared in situ from toluene and sulfuric acid (Zardecki et al., Polish Patent, PL 55230, issued May 15, 1968). 2-Phenylethyl benzoate has also been prepared from 2-phenylethyl alcohol and benzoic anhydride in dichloromethane solvent with vanadium salts as catalysts (Chen, U.S. Pat. No. 6,541,659, issued Apr. 1, 2003) or with bismuth tris(trifluoromethanesulfonate) catalyst (Orita et al., Angew. Chem. Int. Ed. 2000, vol. 39, 2877–2879). It has also been prepared from 2-phenylethyl alcohol and benzoic anhydride in N,N-dimethylformamide solvent with equimolar 1,1,3,3-tetramethylguanidine (Kim et al., Bull. Korean Chem. Soc . 1984, vol. 5, 205–206).
Accordingly, it is an object of this invention to provide a composition including an active or functional organic compound, which is solubilized by a safe and effective organic solvent such as an aryl carboxylic ester of 2-phenylethyl alcohol, e.g. 2-phenylethyl benzoate, 2-phenylethyl toluate or di-2-phenylethyl phthalate.
Another object is to provide a personal care, e.g. a sunscreen, cosmetic, pharmaceutical, agricultural or industrial composition containing a solid, active or functional organic compound which is solubilized.
A specific object of the invention is to provide a sunscreen composition containing active UVA and/or UVB compounds, which are solubilized by a phenylethyl ester, and show excellent performance properties including increased critical wavelength and UVA/UVB absorbance ratio.
A further object herein is to solubilize at least 20%, preferably 30% w/w or more of the active with the solubilizer of the invention.
A specific object of the invention is to provide a process for the synthesis of the solubilizer that economically affords a product with low color and low odor and that has a low environmental impact (no solvents, no stoichiometric reagents, no dangerous by-products, etc.; cf. ‘green chemistry’).
These and other objects and features of the invention will be made apparent from the following description.